insidious

adjective

Definition of insidiousnext
as in treacherous
formal causing harm in a way that is gradual or not easily noticed Most people with this insidious disease have no idea that they are infected. an insidious enemy

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Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Recent Examples of insidious Repass cast the online conversation about irregularities in Johnson County elections as harmful and insidious. — Matthew Kelly, Kansas City Star, 22 Oct. 2026 Perhaps most controversial and, some say, the most insidious of all, is the growing adoption of digital tipping and tipping culture in general across France. — CNN Money, 4 Oct. 2026 Given the chance to go big with his take on insidious zealotry, the Harold & Kumar star is both charming and gargantuan. — David Fear, Rolling Stone, 28 Sep. 2026 For The Times) New research in California’s San Joaquin Valley finds valley fever fungus thriving in urban areas in rodent burrows, revealing a wider, more insidious footprint. — Susanne Rust follow, Los Angeles Times, 24 Sep. 2026 See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
  1. treacherous
  2. subtle
  3. perfidious
  4. deceptive
  5. false
  6. misleading
  7. deceitful
  8. incorrect
Adjective
  • Adapting to these changes while navigating generational turnover can be treacherous.
    — Will Hausberg, Fortune, 4 Nov. 2026
  • Without that or a cord to stop you from picking up debris in hard-to-reach places, vacuuming won’t seem like such a treacherous chore with the V9 Motorbar.
    — Kelsey Fogarty, PC Magazine, 2 Nov. 2026
Definition of treacherous
Adjective
  • One of Yoshitomo Nara’s largest paintings is also one of his most subtle.
    — Daniel Cassady for ARTnews, Robb Report, 4 Nov. 2026
  • With its choppy layers and subtle movement, the cut felt modern, refined, and perfectly in step with her evolving personal style.
    — Amanda Le, InStyle, 4 Nov. 2026
Definition of subtle
Adjective
  • Logan Marshall-Green as Melanthius Melanthius is a perfidious goatherd who sides with Antinous.
    — Hannah Abraham, Forbes.com, 18 July 2026
  • This is perhaps the most perfidious practice of this sort of politics.
    — David M. Drucker, Twin Cities, 3 June 2026
Definition of perfidious
Adjective
  • The agency said undisclosed collection or use of personal information to personalize prices could violate the FTC Act’s prohibition on unfair or deceptive practices.
    — Alexandra Harrell, Footwear News, 3 Nov. 2026
  • The Brennan Center for Justice tested ChatGPT, Gemini, Grok, Claude, Perplexity and DeepSeek for their willingness to facilitate deceptive content.
    — Julia Boorstin, CNBC, 3 Nov. 2026
Definition of deceptive
Adjective
  • Black asserts that the statements made by Garcia are false and that traveling to appear on national television to make such statements about the inquiry into Epstein’s crimes goes beyond the purview of a member of Congress.
    — Claire Carter, The Washington Examiner, 5 Nov. 2026
  • The hotel had something of a false, albeit star-studded, start, opening for just one night in April 2020 (with first guests including stellar artists Hiroshi Sugimoto and Takashi Murakami), before it was closed by the pandemic.
    — Condé Nast, Condé Nast Traveler, 5 Nov. 2026
Definition of false
Adjective
  • Early voting trends and stories about how long the lines are in reliably red or blue districts are tempting to use as data points — but are notoriously misleading.
    — Ben Smith, semafor.com, 3 Nov. 2026
  • The claim featured in the ad was rated misleading, as a series of court records undercut the claim that Hamilton attempted to protect the child abuser.
    — Kansas City Star, Kansas City Star, 3 Nov. 2026
Definition of misleading
Adjective
  • Fielder grills Evans about this later in the film, explaining that receiving a portion of the film’s profits could jeopardize the integrity of the project and make the couple look deceitful.
    — Wesley Stenzel, Entertainment Weekly, 3 Nov. 2026
  • What readers are saying The comments reflect a strong criticism of James O'Keefe and his methods, with many labeling him as deceitful and manipulative.
    — Scott Nover, Washington Post, 22 Oct. 2026
Definition of deceitful
Adjective
  • During the 2022 midterm elections, independent observers from the Carter Center reported significant numbers of voters arriving at incorrect precincts, likely because of changes associated with redistricting.
    — Kathryn Watson, CBS News, 3 Nov. 2026
  • An earlier version of this story included an incorrect name and gender for the victim in the crash, based on information from the highway patrol.
    — Judy L. Thomas, Kansas City Star, 3 Nov. 2026
Definition of incorrect

Browse Nearby Words

inside tracks
insidious
insidiously
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Cite this Entry

“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 6 Nov. 2026.

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